The feature to use GPS coordinates inside geotagged photos as a waypoint to navigate to is an obvious one, but actually a pretty clever use if you think about it. Good job, TomTom.
Instead of writing down addresses when you visit somewhere new, just snap a photo of something at that location and you'll be able to get back there no problem. Need to direct someone to your house, or to a coffee shop? Snap a photo, email that to them and you're done.
Geocachers will be pretty thrilled at this too, having coordinates be integrated into photos of the thing you're looking for.
It's free if you already have the TomTom app, otherwise it's $50 for the US maps, $60 for the US & Canada/US & Mexico. [iTunes]